Measurement Of The Top Anti Top Quark Pair Production Cross Section In The Tau Jets Channel At Square Root Of S
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Measurement Of The Top Anti Top Quark Pair Production Cross Section In The Tau Jets Channel At Square Root Of S
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Author : Teeba Rashid
language : en
Publisher:
Release Date : 2013
Measurement Of The Top Anti Top Quark Pair Production Cross Section In The Tau Jets Channel At Square Root Of S written by Teeba Rashid and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with Hadron interactions categories.
Measurement Of Sigma X Br W Approaches Tau Upsilon Jets Via Precision Tracking In P P Collisions At Square Root Of S
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Author : Robert Andrew Dunn
language : en
Publisher:
Release Date : 1995
Measurement Of Sigma X Br W Approaches Tau Upsilon Jets Via Precision Tracking In P P Collisions At Square Root Of S written by Robert Andrew Dunn and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with categories.
Scientific And Technical Aerospace Reports
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Author :
language : en
Publisher:
Release Date : 1995
Scientific And Technical Aerospace Reports written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with Aeronautics categories.
Government Reports Announcements Index
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Author :
language : en
Publisher:
Release Date : 1993-06
Government Reports Announcements Index written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1993-06 with Science categories.
Measurements Of The Top Anti Top Production Cross Section And Top Quark Mass In The Hadronically Decaying Tau Jets Decay Channel At Cdf
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Author :
language : en
Publisher:
Release Date : 2011
Measurements Of The Top Anti Top Production Cross Section And Top Quark Mass In The Hadronically Decaying Tau Jets Decay Channel At Cdf written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
In this thesis, we present the first exclusive observation of the t-t → hadronic [tau] + jets decay channel. Using these events, we measure the t-t pair production cross section and the top quark mass in 2.2 fb-1 of data collected with the Collider Detector at Fermilab (CDF). The Tevatron accelerator at Fermilab provides collisions of protons and anti-protons at a center-of-mass energy of √s = 1.96 TeV and is one of only two accelerators in the world with enough energy to produce top quarks. With a branching fraction of nearly 10%, the hadronic [tau] + jets decay channel is the third largest t-t decay mode, and it has only been minimally explored. This the first measurement of the t-t pair production cross section in this decay channel at CDF and the first measurement of the top quark mass in this decay channel in the world. The analysis introduces a new method to recover the total momentum of the [nu] produced in the [tau] decay and an artificial neural network to reduce the contribution from the largest background source, QCD multijet background. The t-t pair production cross section is extracted by minimizing a negative log likelihood function which compares the number of observed events to the number of expected events for a given t-t cross section. The top quark mass is extracted by minimizing a negative log likelihood function built from signal and ii background probabilities which are based on the matrix elements for t-t production and decay and W + 4 parton production, respectively. Using events selected with exactly 1 hadronically decaying [tau], exactly 4 jets with at least 1 identified as having originated from a b quark, and large missing transverse energy, we measure the t-t pair production cross section to be 8.8 ± 3.3 (stat.) ± 2.2 (syst.) pb and the top quark mass to be 172.7±9.3 (stat.) ±3.7 (syst.) GeV. We find both values to be in good agreement with previous measurements in other t-t decay channels, and the cross section to be consistent with next-to-leading order theoretical predictions.
Measurement Of The Top Quark Pair Production Cross Section In Pp Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2012
Measurement Of The Top Quark Pair Production Cross Section In Pp Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
The top quark pair production cross section is measured in dilepton events with one electron or muon, and one hadronically decaying tau lepton from the decay t anti-t to (l nu(l)) (tau nu(tau)) b anti-b, where l can be either an electron or a muon. The data sample corresponds to an integrated luminosity of 2.0 inverse femtobarns for the electron channel and 2.2 inverse femtobarns for the muon channel, collected by the CMS detector at the LHC. This is the first measurement of the t anti-t cross section explicitly including tau leptons in proton-proton collisions at sqrt(s)=7 TeV. The measured value sigma(t anti-t) = 143 +/- 14 (stat.) +/- 22 (syst.) +/- 3 (lumi.) pb is consistent with the standard model predictions.
Measurement Of Sigma P Anti P T Anti T In The Tau Jets Channel By The D 1 2 Experiment At Run Ii Of The Tevatron Collider
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Author :
language : en
Publisher:
Release Date : 2008
Measurement Of Sigma P Anti P T Anti T In The Tau Jets Channel By The D 1 2 Experiment At Run Ii Of The Tevatron Collider written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with categories.
The top quark is the heaviest and most mysterious of the known elementary particles. Therefore, careful study of its production rate and other properties is of utmost importance for modern particle physics. The Tevatron is the only facility currently capable of studying top quark properties by on-shell production. Measurement of the top quark pair production cross section is one of the major goals of the Tevatron Run II physics program. It provides an excellent test of QCD at energies exceeding 100 GeV. We report on a new measurement of p{bar p} → t{bar t} production at √ = 1.96 TeV using 350 pb−1 of data collected with the D0 detector between 2002 and 2005. We focus on the final state where a W boson from one of the top quarks decays into a [tau] lepton and its associated neutrino, while the other decays into a quark-antiquark pair. We aim to select those events in which the [tau] lepton subsequently decays to one or three charged hadrons, zero or more neutral hadrons and a tau neutrino (the charge conjugate processes are implied in all of the above). The observable signature thus consists of a narrow calorimeter shower with associated track(s) characteristic of a hadronic tau decay, four or more jets, of which two are initiated by b quarks accompanying the W's in the top quark decays, and a large net missing momentum in the transverse plane due to the energetic neutrino-antineutrino pair that leave no trace in the detector media. The preliminary result for the measured cross section is: [sigma](t{bar t}) = 5.1{sub -3.5}{sup +4.3}(stat){sub -0.7}{sup +0.7}(syst) ± 0.3 (lumi.) pb.
Measurement Of Boldsymbol Ttb Production In The Tau Jets Channel Using Boldsymbol P Bar P Collisions At Boldsymbol Sqrt S
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Author :
language : en
Publisher:
Release Date : 2010
Measurement Of Boldsymbol Ttb Production In The Tau Jets Channel Using Boldsymbol P Bar P Collisions At Boldsymbol Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.
We present a measurement of the t{bar t} production cross section multiplied by the branching ratio to tau lepton decaying semi-hadronically ([tau]{sub h}) plus jets, [sigma](p{bar p} → t{bar t} + X) · BR(t{bar t} → [tau]{sub h} + jets), at a center of mass energy √s = 1.96 TeV using 1 fb−1 of integrated luminosity collected with the D0 detector. Assuming a top quark mass of 170 GeV, we measure [sigma]{sub t{bar t}} · BR{sub [tau]{sub h}+j} = 0.60{sub -0.22}{sup +0.23}(stat){sub -0.14}{sup +0.15}(syst)±0.04 (lumi) pb. In addition, we extract the t{bar t} production cross section using the t{bar t} → {tau}{sub h} + jets topology, with the result [sigma]{sub t{bar t}} = 6.9{sub -1.2}{sup +1.2}(stat){sub -0.7}{sup +0.8}(syst) ± 0.4 (lumi) pb. These findings are in good agreement with standard model predictions and measurements performed using other top quark decay channels.
Measurement Of Single Top Quark Production In The Tau Jets Channel Using Boosted Decision Trees At D0
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Author : Zhiyi Liu
language : en
Publisher:
Release Date : 2009
Measurement Of Single Top Quark Production In The Tau Jets Channel Using Boosted Decision Trees At D0 written by Zhiyi Liu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with Colliders (Nuclear physics) categories.
The top quark is the heaviest known matter particle and plays an important role in the Standard Model of particle physics. At hadron colliders, it is possible to produce single top quarks via the weak interaction. This allows a direct measurement of the CKM matrix element Vtb and serves as a window to new physics. The first direct measurement of single top quark production with a tau lepton in the final state (the tau+jets channel) is presented in this thesis. The measurement uses 4.8 fb1 of Tevatron Run II data in p\bar{p} collisions at \sqrt{s}=1.96 TeV acquired by the D0 experiment. After selecting a data sample and building a background model, the data and background model are in good agreement. A multivariate technique, boosted decision trees, is employed in discriminating the small single top quark signal from a large background. The expected sensitivity of the tau+jets channel in the Standard Model is 1.8 standard deviations. Using a Bayesian statistical approach, an upper limit on the cross section of single top quark production in the tau+jets channel is measured as 7.3 pb at 95% confidence level, and the cross section is measured as 3.4+2.0−1.8 pb. The result of the single top quark production in the tau+jets channel is also combined with those in the electron+jets and muon+jets channels. The expected sensitivity of the electron, muon and tau combined analysis is 4.7 standard deviations, to be compared to 4.5 standard deviations in electron and muon alone. The measured cross section in the three combined final states is sigma(p\bar{p}->tb+X,tqb+X) = 3.84+0.89−0.83 pb. A lower limit on Vth is also measured in the three combined final states to be alrger than 0.85 at 95% confidence level. These results are consistent with Standard Model expectations.
Measurements Of The Top Quark Pair Production Cross Section In Lepton Jets Final States Using A Topological Multivariate Technique As Well As Lifetime B Tagging Inproton Anti Proton Collisions At S 1 2
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Author : Tobias F. Golling
language : en
Publisher:
Release Date : 2005
Measurements Of The Top Quark Pair Production Cross Section In Lepton Jets Final States Using A Topological Multivariate Technique As Well As Lifetime B Tagging Inproton Anti Proton Collisions At S 1 2 written by Tobias F. Golling and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with categories.
Two alternative measurements of the t{bar t} production cross section at {radical}s = 1.96 TeV in proton-antiproton collisions in the lepton+jets channel are presented. The t{bar t} production cross section is extracted by combining the kinematic event information in a multivariate discriminant. The measurement yields {sigma}{sub p{bar p} {yields} t{bar t} + x} = 5.13{sub -1.57}{sup +1.76}(stat){sub -1.10}{sup +0.96}(syst) {+-} 0.33 (lumi) pb in the muon+jets channel, using 229.1 pb{sup -1}, and in the combination with the electron+jets channel 226.3 pb{sup -1} {sigma}{sub p{bar p} {yields} t{bar t} + x} = 6.60{sub -1.28}{sup +1.37}(stat){sub -1.11}{sup +1.25}(syst) {+-} 0.43 (lumi) pb. The second measurement presented reconstructs explicitly secondary vertices to d lifetime b-tagging. The measurement combines the muon+jets and the electron+jets channel, using 158.4 pb{sup -1} and 168.8 pb{sup -1}, respectively: {sigma}{sub p{bar p} {yields} t{bar t} + x} = 8.24{sub -1.25}{sup +1.34}(stat){sub -1.63}{sup +1.89}(syst) {+-} 0.54 (lumi) pb.